Shock and impact forces sustained by mobile electronic systems or devices during usage can be detrimental to the reliability of components within the mobile devices, such as hard disk drives. This may be especially true when mobile devices are in operation. For example, excessive shock force can cause a recording head in a disk drive to contact the spinning disk, resulting in damage to the recording head or disk surface, and leading ultimately to loss of the data stored on the disk.
Various methods are used to protect the hard disk drive from such shock and impact. For example, such methods may include mechanically tuning the HDD actuator to minimize contact force with the disk during a shock or impact event, or embedding an accelerometer in the hard disk drive to detect a free fall and park the HDD actuator prior to an anticipated impact.
However, the free fall detection scheme in particular may be prone to false triggering. User handling of the computer system may cause movement of the system that is interpreted as a freefall event, resulting in unnecessary parking of the hard drive actuator. Similarly, any repetitive motion may also cause undesired frequent triggers of the freefall sensor. Furthermore, the false trigger rate typically increases when the accelerometer is calibrated for greater sensitivity to detect a lower drop height.
Excessive false detection results in unnecessary parking of the hard drive actuator and has a detrimental impact on computer system I/O performance. Excessive parking of the hard drive actuator can result in the interruption of data transfer activities between the hard disk drive and the computer system, and can lead to system stability issues or software application performance issues.